Answer:
12.78 or 12.80 mostly like 12.78
Explanation:
Answer:
350J
Explanation:
Based on the first law of thermodynamics, which is the law of conservation of energy, energy can neither be created nor lost but can only be transformed. This implies that energy input of a system must equate the energy output as no energy can be lost.
In this case regarding an unlit match that contains 1000J of chemical energy. It burns to emit light energy and heat/thermal energy. If the amount of emitted thermal energy measured is 400J and the remaining/left over amount of chemical energy is 250J, this means that the missing amount of energy has been emitted as light energy.
To find the amount of light energy emitted, we say;
Amount of chemical energy - (thermal energy emitted + remaining chemical energy)
= 1000 - (400 + 250)
= 1000 - 650
= 350J
Hence, the amount of light energy emitted is 350J. This satisfies the law of conservation of energy because the output energy is equal to the total energy in the system.
Answer:
Mass of reactant and mass of product must be equal.
Explanation:
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
Explanation:
This law was given by French chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
For example:
In given photosynthesis reaction:
6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂
there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.
Rare earth metals are a group of 17 elements - lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium - that appear in low concentrations in the ground
Answer:
When halogen elements react with group one metals they form halide salts.
Explanation:
The elements of group 17 are called halogens. These are six elements Fluorine, Chlorine, Bromine, Iodine, Astatine. Halogens are very reactive these elements can not be found free in nature. Their chemical properties are resemble greatly with each other. As we move down the group in periodic table size of halogens increases that's way fluorine is smaller in size as compared to other halogens elements. Their boiling points also increases down the group which changes their physical states. i.e fluorine is gas while iodine is solid.
When halogen elements react with group one metals they form halide salts.
Alkali metals have one valance electron and halogens needed one electron to complete the octet thus alkali metals loses one electron which is accepted by halogens atom and form ionic compound called halide salts.
For example:
2Na + Cl₂ → 2NaCl
2K + Cl₂ → 2KCl
2Rb + Cl₂ → 2RbCl
2Li + Cl₂ → 2LiCl
With bromine:
2Na + Br₂ → 2NaBr
2K + Br₂ → 2KBr
2Rb + Br₂ → 2RbBr
2Li + Br₂ → 2LiBr
With iodine:
2Na + I₂ → 2NaI
2K + I₂ → 2KBI
2Rb + I₂ → 2RbI
2Li + I₂ → 2LiI
